(Official January 1, 2007)

System suitability solution— Dissolve about 45 mg of USP Isopropyl Myristate RS and 5 mg of USP Isopropyl Palmitate RS in 10.0 mL of n-hexane.

Assay preparation— Dissolve 125 mg of Isopropyl Myristate in 25.0 mL of n-hexane, and mix.

Chromatographic system (see Chromatography 621)— The gas chromatograph is equipped with a flame-ionization detector and a 4-mm × 1.8-m column packed with 10% liquid phase G8 on 100- to 120-mesh support S1A. The carrier gas is nitrogen, flowing at a rate of 45 mL per minute. The column temperature is programmed to rise from 90 to 210 at a rate of 2 per minute and then to maintain at 210 for 8 minutes. The detector temperature is maintained at 280, and the injection port temperature is maintained at 240. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times for isopropyl myristate and isopropyl palmitate are about 1 and 1.3, respectively; the resolution, R, is not less than 6.0 between the peaks due to isopropyl myristate and isopropyl palmitate; the tailing factor for the isopropyl palmitate peak is not more than 2; and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Inject about 5 µL of the Assay preparation into the chromatograph, record the chromatogram, and measure the responses for the major peaks. Calculate the percentage of C17H34O2 in the portion of Isopropyl Myristate taken by the formula: in which A is the isopropyl myristate peak response; and B is the sum of the responses of all the peaks in the chromatogram, except the solvent peak.